The objective of this proposal is development of an advanced metal tagging systems and methodology, which in combination with an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) detector will provide researchers and clinicians with substantially improved analytical and prognostic capabilities. ICP-MS as an analytical detector possesses decisive advantages that enhance the performance of immunoassays, including: i) high precision;ii) low detection limits;iii) large dynamic range;iv) independence of non-specific background and analytical response from incubation or storage times (as protein degradation does not affect analysis of an elemental tag);v) larger multiplexing potential (potentially, up to 167 isotopes;realistically, around 100 distinguishable tags. Mismatch of excitation and absorption wavelengths, and overlap of emission signals are physical characteristics of fluorophores (including quantum dots), which represent a critical barrier to progress in the field of multiplexed assays and cannot be eliminated. A key feature of our approach is the development of tagged affinity products designed for specific recognition of distinguishing cell surface and intracellular markers and targeted for the ICP-MS detection. Methods of labeling with distinguishable stable isotopic elemental tags will be developed. This project will deliver stable metal tags, appropriately tagged affinity reagents, methods and demonstrative data for the distinction of multiple analytes. We hope that this integrated reagent system will dramatically enhance the diagnostic, prognostic and therapeutic efficacy available to physicians and their patients, increasing the effectiveness of healthcare while substantially reducing the human and financial costs of modern personalized treatment. Our interdisciplinary group of recognized experts will address this significant challenge. Professors Mitchell A. Winnik and Mark Nitz will use existing capabilities to synthesize the carrier polymers. Methods of tagging with distinguishable stable isotopic elemental tags will be developed. The ICP-MS group (Vladimir I. Baranov) will develop a purpose specific analytical methods combining robotic sample introduction with an ICP-MS instrument that will allow multiplex detection. Development of the elemental tagged assay methodology will be conducted by Olga I. Ornatskaia using existing capabilities and in constant verification against conventional assay methods.